Circuit interrupter



May 23, 1944. J. SLEPIAN 2,349,631l

C IRCUIT INTERRUPTER Filed May 24, 1941 5 5 l E l Patented May 23, 1944cmcmr maxaman Joseph siepi, Pittsburgh, n., signor to westinghouseElectric da Manufacturing Company, East Pittsburgh, Pa., a corporationof Pennsylvania Application May 24, 41941, Serial No. 394,981

(Cl. ztlohli) 6 Claims.

This invention relates to circuit interrupters, and more particularly tocircuit interrupters of the air break type utilizing a blast of gas toassist arc extinction.

A study of the fundamental processes covering arc extinction in gasblast circuit interrupter indicates quite definitely that the functionof the gas blast is to so place and so alter the configuration of alength of arc that the diffusive forces such as heat conduction anddeionization are greatly enhanced. It has been determined that the mostfavorable arc configuration for diffusive effects is a relatively longarc of very small cross section. In addition, turbulence in the gas flowwill .increase the effective diffusion coeiiicient and also the thermalconductivity coeilicient so asto improve the arc extinguishing action.

In the gas blast circuit interrupters of the prior art, both the nozzleand cross blast types, arc extinction is accomplished by reducing thecross section of a relatively short length of arc by the action of ablast of gas thereon. A large part of the gas blast, however, in theseinterrupters during the greater part of the circuit interruptingoperation flows remotely from the reduced section of arc so that it isin a sense wasted. For this reason, verylntense blasts of gas arenecessary to bring about arc extinction.

The present invention has for its object the provision of a circuitinterrupter of the gas blast type which, by a more effective utilizationof the blast of gas, brings about arc extinction with a materially lowergas blast pressure and much smaller quantity of gas than heretoforerequired.

It is another object of my invention to provide arc extinguishing meansfor circuit interrupters of the gas blast type which when acting upon anarc produces a configuration of arc most favorable for arc extinction.

More specifically, my invention embraces an arc chute for circuitinterrupters of the gas blast type of such design that even as the arcsection is reduced, the full gas blast continues to act upon it so as tofurther reduce the section Without any gas being able to pass around thereduced section. This may be accomplished by blowing the arc after it isdrawn on to diverging arc horns within a chute having insulating wallswhich converge in proportion as the are length from horn to hornincreases.

Other objects and advantages will appear in the following descriptionwhen read in connection with the accompanying drawing, in which:

Figure 1 is a side view partially in section showing a circuitinterrupter embodying my invention,

Fig. 2 is a longitudinal sectional view of the arc chute of theinterrupter shown in Fig. 1, taken along the line II-II -thereof withthe moving contact in open position,

Figs. 3, 4f and 5 are cross sectional views of the arc chute of theinterrupter shown in Fig. 1, taken respectively along the lines IIL-III,IV- IV and V-V.

Referring to the drawing, the reference numeral 'I designates a panelpreferably of insulating material upon which is mounted a pair oflead-ln conductors 3 and il. The lead-in conductors are preferablyinsulated in part by bushings I3 and I5. The right-hand end of lead-inconductor 9 carries a stationary contact assembly I1 which may beenclosed in a housing I9 of insulating material and secured to the endof bushing I3 f or support. Coacting with the stationary contactassembly l1 is a movable contact member 2l, the lower portion of whichis bifurcated and pivotally joined at 23 to a conducting bracket 25secured to the lower lead-in conductor Il.

The movable contact member 2l is operative about the pivotal support 23into and out of engagement with the stationary contact I1 by anoperating mechanism which may comprise a bell crank 2l connected throughan insulating operating rod 29 to the contact member 2l. The bell crank2l which is pivoted at 3| to .a suitable framework 33 may be actuated bya rod 35 connected to` a rocker arm 31 also pivoted to the frame 33.'I'he rocker arm 31 may be actuated by a suitable operating device, notshown, as for example a solenoid or motor driven mechanism or apneumatic engine, all of which are well known in the art and need not befurther described.

Supported upon the housing I! is an arc chute generally designated at 39comprising fan shaped side members Il and a pair of diverging enclosingmembers 43. A pair of arc terminal members 45 are disposed along theinner surfaces of the side enclosure members 43 and extend from thelower end of the chute 33 upwardly to substantially the upper endthereof. The space between the diverging arc terminal members 45 islined with a pair of wall members l1 preferably of insulating material,which is of a refractory nature and does not emit gas in an appreciableamount when subjected to the heat of the arc, and which also maintains ahigh resistance when subjected to the heat of the arc.

The wall members 41 are inclined with respect to each other so as toform an arc passage which converges in a direction away from thei loweror stationary contact end of the arc chute. The

degree of convergence, as more clearly shown in' 'Ihe lower end of theleft-hand arc terminal' member 45 makes contact with an arcing contact49 connected to the lead-in conductor 3. The right-hand arc terminalmember 45 is provided with a resilient arcing member -l adapted to makesliding contact with the movable contact 2| during the opening movementof the latter. In operation, an arc established between the stationarycontact l1 and the moving contact 2| is moved upwardly onto the arcingcontacts 43 and 5I from whence it transfers to the arc terminal members45.

Arc movement and arc extinction are preferably produced by a blast oi'arc extinguishing gas, such as compressed air. 'I'he requisite blast ofcompressed gas is. preferably directed at right y angles to the arcthrough a tube 53 of insulating material which joins the lower end ofthe casing I9 as more clearly shown in Fig. 1, and is held in positionby the conducting bracket 25.

I have discovered that eiective operation of the interrupter may beobtained with only a relatively low pressure source of compressed gas.Compressed gas for circuit interruption may be obtained from anysuitable source such as a storage reservoir or from a compressor securedtoV and operated by the contact operating mechanism. 'I'he fact thatonly a small quantity of.

compressed gas at a relatively low pressure is needed, makes the latterarrangement feasible. The form of compressor which may be used is shownin Fig. 1 and comprises a cylinder 55 secured to the lower end of thetubular insulator 53.

The cylinder 55 has a piston 51 operable therein by means of aconnecting rod 59 extending through the lower end of the cylinder. Theconnecting rod 59, for example, may be coupled by a link 6I to therocker arm 31 ot the contact operating mechanism. 'I'hus when the rockerarm 31 is rotated in a clockwise direction so as to actuate the movingcontact 2l to the open circuit position, the piston 51 will be movedupwardly within the cylinder 55 to cause a blast of gas to low throughthe tubular insulator 53 and into engagement with the arc drawn betweenthe separating contacts to force the arc upwardly into the arc chute 39.As heretofore described, the walls 41 are spaced farther apart at thelower or contact end of the chute and narrow in proportion with thedivergence of the arc terminal members 45.

'I'he arc drawn between the arcing members 43 and 5I is moved upwardlyand transverse to the diverging arc terminal members 45. As the arcmoves upwardly, it is progressively lengthened but at the same time ismoved into correspondingly narrower portions of the arc chute. Thecontinually narrowing arc path, therefore, subjects the arc to a moreeffective gas iiow. In fact, the dimensions of the chute are soproportioned that the arc substantially obstructs the gas ow and therebyprevents the wastage of gas which would otherwise flow around the are,For

some applications. it has been found' desirable to maintain asubstantially constant gas velocityV with respect to the entire lengthof the arc. `To do this. the walls of the arc chute may be soproportioned that the cross section of passage relmains substantiallyconstant valong the entire length of the arc chute.

As the current reduces in intensity i'n approaching a current zero, thearc is carried by the gas blast to narrower and longer sections. of thechute so that at current zero it has the long length and narrow sectionmost favorable for arc extinction. For interrupting 50,000 amperes at k.v. and at 60 cycles per second. I have found that satisfactory resultscan be obtained with an arc chute o! approximately 50" in length and anarc passage therethrough of approximately 3 square inches in crosssection. Furthermore, it has been determined that an arc passage of 1" x3" at the section shown in Fig. 5, of $4" x 12" at the section shown inFig. 4 and of $43" x 24" at the section shown in Fig. 3 gives adesirable arc chute coniiguration. I also found that satisfactoryresults can be obtained when air pressures as low as 6 to 10 pounds persquare inch were used. 'Ihe eiilciency of the foregoing structure isfurther exemplified in that ouh/.450 cubic inches of compressed air atthe above named pressures, is required to bring about complete circuitinterruption.

Although I have shown and described a particular circuit interruptingstructure and have given specific dimensions of certain parts thereof,it is to be understood that the same is for the pmpose of illustrationand that changes and modications may be made by those skilled in the artwithout departing from the spirit and scope of the appended claims.

I claim as my invention:

1. In a circuit interrupter, means for establishing an arc, means forextinguishing said arc comprising means at least partially of insulatingmaterial deiining a slot-like arc passage, and means for moving said arciateraliywithin said arc passage, said means of insulating materialbeing so arranged that said passage decreases in width in the directionof arc movement and increases dimensionally generally longitudinally Yout the length of the arc passage.

2. In acircuit interrupter, means for establishing an arc, a pair ofdiverging arc terminal members for receiving said arc, means for movingthe terminal ends of said arc along said arc terminal members, and meansof insulating material enclosing at least the sides of the space betweensaid arc terminal members, said means of insulating material being soarranged to provide an arc passage of substantially uniformcross-sectional area throughout its length.

3. In a circuit interrupter of the gas blast type, an arc chuteincluding a pair of spaced walls of insulating material, diverging archorns disposed between said walls and forming closures for the sideedges of said chute, means for establishing an arc between the convergedends of said arc horns, and means for directing a blast of gas betweensaid arc horns for moving said arc along said arc horns, the spacing ofsaid walls between said arc horns narrowing in proportion to theincrease in arc length as the arc is moved along said arc horns.

4. In a circuit interrupter, a substantially fan- Shaped arc chutehaving a narrow passage therethrough said passage having a substantiallyuniform cross-section throughout its length, means external to said arcchute for supplying a blast of gas, separable contact means forestablishing an arc across the converged endy of said chute, and meansfor subjecting said arc to a lateral blast of gas from said externalmeans for moving said arc into said chute to lengthen the same withinsaid chute to cause its interruption.

5. In a circuit interrupter, a substantially fanshaped arc chute havinga narrow passage therethrough, said passage having a substantiallyuniform cross-section throughout its length, separable contact means forestablishing an arc across the converged end of said chute, operatingmeans actuating said contact means, and means operatlve in response tomovement of said operating means for causing a blast of gas to ilowagainst said arc and moveA it laterally into said arc chute.

6. In a circuit inten'upter, a substantially fanshaped arc chute havinga narrow passage therethrough, said passage having a substantiallyuniform cross-section throughout its length, separable contact means forestablishing an arc across the converged end of said chute, operatingmeans actuating said contact means, and means including a pistonactuated by said operating means in response to an opening movement ofsaid contact means for causing a blast of gas to ow against said arc andmove it into said arc chute.

JOSEPH SLEPIAN.

